Ok, our house will be built in rainy, and seismically active, western Oregon. I thought I had it all figured out, but now I am not so sure. It will be one floor above a walk-out basement. Here is my problem.
I was planning to use ICFs for all the walls, basement as well as first floor. But, many corners are not at 90-degrees with quite a few short walls with lots of windows, all of which complicates everything with ICFs especially in a seismic zone. Because of these things, the ICF prescriptive design code can’t be used. So, my whole plan is now up in the air.
Therefore, I have been looking at SIPS, for the first floor walls (and maybe the roof too), but I wonder about them in the rainy climate. Most of them are OSB and no one likes OSB especially if it ever gets wet. The joints seem to me that they would be a potential weakness forever too.
What do you guys recommend?
Have I missed any other good alternatives?
Should I stick to the ICFs and massively beef them up with thickness and rebar to meet the design codes – probably requiring full engineering too?
Thanks
Replies
gerrha,
I have what you want to build, that is SIP's over ICF's If I were to do it all over I would do ICF's all the way to the top cap (or ridge line).. ICF's are amazingly flexible once you have begun to understand them and how to modify the form to ensure it will work.
Remember ICF's are simply forms.. the concrete and rebar are the strength, basically you are building with concrete at the same time you are insulating it. Your design calls for other than 90 degree corners, so what! Most companies have 45 degree corners and some even have 30 degree corners..
I needed 7 1/2 degree corners so I made my own. I simple cut the forms at 7 1/2 degrees on my table saw and then made a wooden buck to hold the form at that angle. Then I screwed the wooden buck into the webs that sheet rock is normally screwed into.. that kept the forms together during the pour and when the pour was over I could have simply removed the wooden bucks. I didn't because I used white oak boards and had planned and surfaced them so they were already finished..
As for worring about SIP's in the rain!
nonsense!
They use a pretty water proof OSB (at least R control does) and my house which took me over 4 years to finish to the point where I put shingles on parts of the roof had the OSB of the SIP exposed to rain, snow, and all the weather Minnesota can put out.. when I went to shingle that part of the roof there was some slight swelling but the OSB was plenty sturdy and solid.
I can understand how OSB which is going to be used under carpet or other flooring could swell and cause problems but my R control panels didn't cause me a bit of trouble even exposed to everything for 4 years..
Hi Frenchy,
I know that all of the companies make angled ICF corners, but once you deviate from 90-degrees in a seismic zone, especially a D1 zone as is western Oregon, the prescriptive design code is no longer valid and then many other issues start to surface like unbalanced backfill height, wall height, position of the first floor walls over the basement walls, solid wall length, etc. It might turn out that I would need to have 10" thick concrete with tons of rebar on the first floor over the basement, plus a full seismic engineered design, which I was hoping to avoid.
I have this whole house designed based on ICF, but with these seismic issues, I was starting to look at alternatives like the SIPs. If I get what you are saying though, a good rain screen exterior design should be just fine with the OSB of SIPs. How about the joints? They just seem like a weakness to me both in terms of energy loss, consistency in joining them along a wall, and long term sealing issues.
However, just tell me that the ICFs will be better and how to solve this seismic stuff and I will be very happy and will forget about the SIPs.
Thanks
gerrha,
Sesmic? Minnesota doesn't allow earthquakes, that's for you shifty west coasters ;-) Actually they are simply forms.. They hold concrete, the concrete and rebar are the strength.
OK try this exercise. Instead of a 90 degree corner what changes if the form came out slightly wrong and became 80 degrees? or 100 degrees? , you still have X amount of 4000PSI concrete held together by the same rebar..
The issues you speak about are more a matter of is your design solid and safe than what you build it with. If you have a weak design or poor site you could build with timbers, 2x4's, SIP's, or ICF's and have the same issues..
It sounds like we need to discuss forms and load paths etc.. I have no formal training there so whenever I have a question I speak with my architect BIL who gives me advice.. I then add extra to meet my standars and move on.
Some things are pertty well known.. for example an arch is a strong way to build. So if you have a choice between square corners and round if you can figure out how to build affordably in the round it will be stronger than 90 degree corners.
triangles are stronger than squares etc..
you know just basic stuff..
Edited 12/13/2007 7:21 am ET by frenchy
Hi Frenchy,
Well, I think the seismic problems with the concrete are that it has large mass, does not flex well, and can fail quickly. Wood frame, and I am sure the SIPs, have so much less mass and flex enough not to be nearly as much of a problem as concrete.
Like you, I am not exactly sure why a non 90-degree corner is such a problem, but it must be as that immediately drops you out from being able to use the prescriptive design code.
Hopefully an engineering somebody will help me out here.
I'm also in Western Or., on the south coast and a builder to boot with a few ICF foundations under my belt.
Once you deviate from the prescriptive codes you'll need your foundation engineered (might have to anyway with the backfill issue) but, in Corvallis, finding an engineer should be a snap. I use an engineer in Bend, because I can send blueprints on a large format fax and it costs really no more than getting a local engineer.
I use AARX forms, in large part because they have a plant near Portland and your shipping will be much less, plus their classes (which you DO want to do) are readily available locally.
SIPs can be a bit of a pain to get in our area.
I was going to use them in a new custom house three years ago, and contacted a couple mfgr's in the Seattle area (closest ones at the time) I couldn't even get a return phone call.
Best of luck.
There is a company in Newport Ore. ,MapleBrook Engineering Inc. They handle SIPS (Premier) and ICFs . Brandon Helms is the owner and is a licensed P.E. in several western states. I am looking at building a SIP addition and have talked to him a couple of times. You can reach him at 541-574 1855 or http://www.Maple-Brook.com. Good luck.
Keith
I recently attended an EXPO where there about eight ICF companies represented. One of those which impressed me was http://www.quad-lock.com of Surrey, BC.
Their corner hardward options include one which can be adjusted to any angle.
According to the company info, this line of ICFs has been used in Europe for twenty years or more. One thing that was easy to see, their foam is much denser than any of the others I looked at that day, including all the major manufacturers.
There are at least two types of ICFs. The more common type uses only polystyrene as the form (with perhaps some type of steel or plastic ties and/or reinforcement) while another type uses a mix of cement or lightweight concrete and either polystyrene pellets or wood chips. Examples of this latter type is Rastra, Techblock, Cempo, Durisol, and Faswall.
I am designing a house and an artist studio along the Columbia River in Oregon (Wasco County) and decided to go with Faswall. My reason was because I am building in an area that has been and will be swept with wildfires and I wanted something more fire resistant than regular polystyrene ICFs. The other reason is that I have ants that crew through and nest in pink fiberglass insulation and I figure that the would have a field day playing in polystyrene.
I chose Faswall as they have a productio faciity just outside Corvallis (maybe Philomath) and I figured that I could take my trailer down there and haul them back to save on shipping. I had Dan Symons Engineering in Portland (S.W. Foster Rd.) do the engineering. If you want more information on them, I can dig out their email address or phone number. I haven't actually started construction yet, but should be able to give you more information in the spring when I hope to get under way.